(Formerly LiveScript) Netscape's simple, cross-platform, World-Wide Web scripting language, only very vaguely related to Java. JavaScript is intimately tied to the World-Wide Web, and currently runs in only three environments - as a server-side scripting language, as an embedded language in server-parsed HTML, and as an embedded language run in browsers.
JavaScript originated from Netscape, and for a time, only Netscape products supported it. Microsoft now supports it, but as a "work-a-like" called JScript. The resulting inconsistencies make it difficult to write JavaScript that behaves the same in both Netscape Navigator and Microsoft Internet Explorer. This could be attributed to the slow progress of JavaScript through the standards bodies. Opera supports ECMAScript. ECMAScript is the standardized version of JavaScript Core.
JavaScript runs "100x" slower than C, as it is purely interpreted (Java runs "10x" slower than C code). Netscape and allies say JavaScript is an "open standard" in an effort to keep Microsoft from monopolising web software as they have desktop software. Netscape and Sun have co-operated to enable Java and JavaScript to exchange messages and data.
JavaScript should not be confused with Java, and is a Netscape, not Sun trademark.